End-to-side pudendal nerve anastomosis for the creation of a new reinforcing anal sphincter in dogs

Sato, T Konishi, F Kanazawa, K

T. Sato et al., End-to-side pudendal nerve anastomosis for the creation of a new reinforcing anal sphincter in dogs, SURGERY, 127(1), 2000, pp. 92-98

24

INGLESE

Article

Surgery,"Medical Research Diagnosis & Treatment

SURGERY

0039-6060 → ACNP

127

1

2000

92 - 98

ISI

0039-6060(200001)127:1<92:EPNAFT>2.0.ZU;2-L

Background. An ideal reinforcing neo-sphincter should be innervated by the pudendal nerve to work in coordination with the external anal sphincter. Th e aim of this study was to create a skeletal muscle innervated by the puden dal nerve without inducing external anal sphincter morbidity. Methods, Seven dogs were used. On the right side of each dog, the distal en d of thr transected nerve innervating the biceps femoris muscle was anastom osed to the perineural window of the pudendal nerve, where the epineurium w as excised over a small area without injuring the funiculus. Reinnervation was studied 5 months after the operations. The left side of the dogs was us ed as a control. Results. For all 7 dogs, there was no macroscopic difference detected in th e external anal sphincter: For 6 dogs, the biceps femoris muscle was preser ved after end-to-side pudendal nerve anastomosis. After the pudendal nerve central to the anastomosis site was electricallly stimulated, the external anal sphincter contracted in all dogs. After end-to-side pudendal nerve ana stomosis, the biceps femoris muscle contracted with the evoked potential in 5 dogs (71 %) and demonstrated electric activity at rest in 3 dogs (43 %) but there was no reflex activity after anal stimulation. The ratio of type 1 to type 2 muscle fiber in the biceps femoris muscle after end-to-side pud endal nerve anastomosis significantly changed and became the same as that i n the external anal sphincter. The diameter of type type 2 muscle fibers in the biceps femoris muscle significantly decreased after surgery. In additi on, regenerated myelinated axons were observed in a cross section of the an astomosed nerve in 6 dogs. Conclusion. End-to-side pudendal nerve anastomosis is a promising technique for the creation of an anal sphincter in patients who have fecal incontine nce. The technique preserved the original external anal sphincter and creat ed a skeletal muscle that was innervated by the pudendal nerve in 71 % of t he dogs studied. This newly innervated skeletal muscle was capable of contr acting in coordination with the original external anal sphincter on electri c stimulation and also demonstrated characteristics closely similar to thos e of the external anal sphincter.